Method of assembling semiconductor devices with leds

ABSTRACT

Methods of forming integrated circuit packages having an LED molded into the package, and the integrated circuit package formed thereby. An integrated circuit including one or more semiconductor die, passive components and an LED may be assembled on a panel. The one or more semiconductor die, passive components and LED may all then be encapsulated in a molding compound, and the integrated circuits then singularized to form individual integrated circuit packages. The integrated circuits are cut from the panel so that a portion of the lens of the LED is severed during the singularization process, and an end of the lens remaining within the package lies flush with an edge of the package to emit light outside of the package.

CLAIM OF PRIORITY

This application is a divisional of U.S. patent application Ser. No.11/129,637 filed May 13, 2005, entitled “Method of AssemblingSemiconductor Devices With LEDS”, which application is incorporatedherein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present invention relate to methods of formingintegrated circuit packages having an LED molded into the package, andthe integrated circuit package formed thereby.

2. Description of the Related Art

The strong growth in demand for portable consumer electronics is drivingthe need for high-capacity storage devices. Non-volatile semiconductormemory devices, such as flash memory storage cards, are becoming widelyused to meet the ever-growing demands on digital information storage andexchange. Their portability, versatility and rugged design, along withtheir high reliability and large capacity, have made such memory devicesideal for use in a wide variety of electronic devices, including forexample digital cameras, digital music players, video game consoles,PDAs and cellular telephones.

While a number of packaging configurations are known, flash memorystorage cards may in general be fabricated as system-in-a-package (SiP)or multichip modules (MCM), where a plurality of dice are mounted on asubstrate. The substrate may in general include a rigid base having aconductive layer etched on one or both sides. Electrical connections areformed between the dice and the conductive layer(s), and the conductivelayer(s) provide an electric lead structure for integration of the diceinto an electronic system. Once electrical connections between the diceand substrate are made, one or both sides of the assembly are thentypically encased in a molding compound to provide a protective package.

In view of the small form factor requirements, as well as the fact thatflash memory cards need to be removable and not permanently attached toa printed circuit board, such cards are often built of a land grid array(LGA) package. In an LGA package, the semiconductor die are electricallyconnected to exposed contact fingers formed on a lower surface of thepackage. External electrical connection with other electronic componentson a host printed circuit board is accomplished by bringing the contactfingers into pressure contact with complementary electrical pads on theprinted circuit board. LGA memory packages are ideal for flash memorycards in that they have a smaller profile and lower inductance than pingrid array (PGA) and ball grid array (BGA) packages.

Significant economies of scale are achieved by forming a plurality ofintegrated circuit (IC) packages at the same time on panels. Infabrication, the chips and other circuit components are mounted on thepanel, which may be for example a substrate or leadframe, and molded inepoxy molding compound. Once fabricated, the IC packages are separatedfrom the panel, and those which pass inspection may then be enclosedwithin an outer plastic lid to form a completed flash memory card.

After the molding process, it is known to physically and electricallyattach a liquid crystal diode (LED) to a portion of the substrateoutside of the molded package. In the finished flash memory, the LED maybe illuminated by a controller within the IC package, for example toindicate when read/write operations are being performed on the flashmemory. Conventionally, the LED is positioned outside of the moldedpackage.

SUMMARY OF THE INVENTION

Embodiments of the present invention relate to methods of formingintegrated circuit packages having an LED molded into the package, andthe integrated circuit package formed thereby. In embodiments, anintegrated circuit package according to the present invention may befabricated by assembling a plurality of integrated circuits on a panel,which may be for example a PCB substrate, leadframe or TAB tape. Theintegrated circuit may include one or more semiconductor die, passivecomponents and the LED. Once assembled on the panel, the one or moresemiconductor die, passive components and LED are all encapsulated in amolding compound, and the integrated circuits are then singularized toform individual integrated circuit packages.

In embodiments of the invention, the integrated circuits are cut fromthe panel so that the one or more die and passive components areentirely contained and enclosed within each singularized package.However, a lens of the LED is positioned within the molding compoundsuch that a portion of the lens is severed during the singularizationprocess. The result is that the end of the lens remaining within thesingularized package is flush with an outer edge of the package, andcapable of emitting light outside of the integrated circuit package. Inembodiments, the integrated circuit package may then be mounted withinan outer lid to form any of a variety of integrated circuit devicesincluding an SD flash memory and a dual SD/USB flash memory. Theembedded LED may be used in other integrated circuit devices.

The integrated circuit package including an embedded LED may be used ina variety of ways. For example, the embedded LED may be used to confirmproper installation of the integrated circuit package into a hostelectronic device. Alternatively or additionally, the LED may be used toindicate a read/write operation from/to the integrated circuit device.The embedded LED may be used to provide other visual indications of astate of the integrated circuit package.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart of the method of fabricating an integrated circuitpackage having an LED molded into the package.

FIG. 2 is a top view of a panel of integrated circuits including die,components and LEDs during the fabrication process according to thepresent invention.

FIG. 3 is a cross-sectional view through line 3-3 in FIG. 2.

FIG. 4 is a top view of a panel of molded integrated circuits accordingto the present invention prior to being cut into individual integratedcircuit packages.

FIG. 5 is an enlarged view of a pair of integrated circuits with theinternal components and cut lines shown.

FIG. 6 is a top view of an integrated circuit package according to thepresent invention.

FIG. 7 is an edge view though line 7-7 in FIG. 6.

FIGS. 8 and 9 are perspective and top views of a flash memory cardincluding the integrated circuit package of FIG. 6 mounted in a top andbottom lid.

FIG. 10 is a top view of a flash memory card according to an alternativeembodiment including the integrated circuit package of FIG. 6 mounted ina top and bottom lid.

FIG. 11 is a perspective view duel flash memory card including anintegrated circuit according to the present invention.

FIG. 12 is a flowchart of a method of using the embedded LED to confirmproper installation of the integrated circuit package and/or read/writeoperations according to the present invention.

FIG. 13 is a top view of a panel of molded integrated circuit packagesaccording to an alternative embodiment of the present invention prior tobeing cut into individual integrated circuit packages.

FIG. 14 is an enlarged view of a pair of integrated circuits of FIG. 13with the internal components and cut lines shown.

DETAILED DESCRIPTION

Embodiments of the invention will now be described with reference toFIGS. 1 through 14 which relate to relate to methods of formingintegrated circuit packages having an LED molded into the package, andthe integrated circuit package formed thereby. It is understood that thepresent invention may be embodied in many different forms and should notbe construed as being limited to the embodiments set forth herein.Rather, these embodiments are provided so that this disclosure will bethorough and complete and will fully convey the invention to thoseskilled in the art. Indeed, the invention is intended to coveralternatives, modifications and equivalents of these embodiments, whichare included within the scope and spirit of the invention as defined bythe appended claims. Furthermore, in the following detailed descriptionof the present invention, numerous specific details are set forth inorder to provide a thorough understanding of the present invention.However, it will be clear to those of ordinary skill in the art that thepresent invention may be practiced without such specific details.

A method for forming an integrated circuit package having an LED moldedinto the package will now be described with reference to the flow chartof FIG. 1 and the different views of the integrated circuit package atvarious stages in its fabrication in FIGS. 2 through 7. The fabricationprocess begins in step 50 with a panel 100 (FIGS. 2 and 3). The type ofpanel 100 used in the present invention is not critical and may forexample be a substrate in the form of a printed circuit board (“PCB”), alead frame, a tab automated bonding (“TAB”) tape or other known base onwhich integrated circuits may be assembled and encapsulated. In anembodiment, panel 100 may be a PCB substrate formed of a dielectric corehaving a conductive layer formed on the top and/or bottom surface of thecore. In step 52, a conductance pattern may be formed on one or bothconductive layers of panel 100 to establish an electrical connectionbetween the components mounted on panel 100. The conductance pattern mayfurther include contact pads, lead fingers or other external connectorsfor electrical connection between the integrated circuit components andexternal electronic devices.

A plurality of discreet integrated circuits 102 may be batch processedon panel 100 to achieve economies of scale. Each of these integratedcircuits may then be encapsulated and singulated to form a plurality ofintegrated circuit packages as explained hereinafter. Each integratedcircuit 102 being formed on panel 100 may include one or more passivecomponents 104 surface mounted to panel 100 in step 54. The type andnumber of passive components 104 is not critical to the presentinvention and may vary widely in alternative embodiments. In anembodiment, the passive components 104 may include capacitors and/orresisters physically and electrically coupled to panel 100 as is knownin the art.

Each integrated circuit 102 may further include a light emitting diode(“LED”) 108 surface mounted to panel 100 in a step 56. Each LED 108includes a diode 110 for emitting light upon receipt of an electricalcurrent, and a lens 112 for focusing the emitted light. The LED 108 inthe finished integrated circuit package is in communication with acontroller in the package. As explained in greater detail hereinafter,LED 108 may be included to provide a visual indicator of a state of theintegrated circuit package when in use. A diode and lens, which may bemodified and used according to the principals of the present invention,may be provided, for example, by SunLED Co. of Kowloon, Hong Kong. Inembodiments of the present invention, lens 112 may be formed of plasticand may be elongated in comparison to lenses used in conventional LEDs.It is understood that lens 112 may be formed of materials other thanplastic, and may be of conventional length in alternative embodiments ofthe present invention.

Each integrated circuit 102 may further include one or moresemiconductor die mounted to panel 100 in step 58 in a known adhesive oreutectic die bond process, using a known die-attach compound. The numberand type of semiconductor die 114 may vary greatly in alternativeembodiments of the invention. In one embodiment, the one or more die mayinclude a flash memory array (e.g., NOR, NAND or other), S-RAM or DDT,and/or a controller chip such as an ASIC. Other semiconductor die arecontemplated. Where a plurality of die are provided, they may bearranged in a system-in-a-package (SiP) or a multi-chip module (MCM)configuration. Other arrangements are contemplated. The one or more die114 may be electrically connected to panel 100 by wire bonds 116 in step60 in a known wire-bond process.

While the mounting of the passive components, the LED and thesemiconductor die are disclosed as separate steps in the flowchart FIG.1, it is understood that these steps may be performed in differentorders, and altogether in alternative embodiments. Although notspecifically shown on the flowchart of FIG. 1, various visual andautomated inspections may be made during the above-described fabricationof the plurality of integrated circuits on panel 100.

Once the plurality of integrated circuits 102 have been formed on panel100, each of the integrated circuits 102 may be encapsulated with amolding compound 120 in step 62 and as shown in FIGS. 3 and 4. Moldingcompound 120 may be an epoxy such as for example, Novalac, available forexample, from Siliconware Precision Industries Co., Ltd., of Taichung,Taiwan. The molding compound may be applied according to variousprocesses, including by transfer molding or flood molding techniques toform a unitary encapsulation on panel 100 encompassing all of theintegrated circuits 102. In accordance with the present invention, LED108 may be encapsulated within the molding compound along with the oneor more die 114 and passive components 104.

After molding step 62, a marking can be applied to the molding compound120 in step 64. The marking may for example be a logo or otherinformation printed on the surface of the molding compound for eachintegrated circuit. The marking may for example indicate manufacturerand/or type of device. Marking step 64 may be omitted in alternativeembodiments of the present invention.

Each of the integrated circuits 102 may then be singulated in step 66.Singulation step 66 involves cutting integrated circuits 102 on panel100 into a plurality of individual integrated circuit packages. As usedherein, the term cutting is used to refer to cutting, sawing, punchingor other methods used to separate the integrated circuits 102 intoindividual integrated circuit packages. Known cutting devices include,for example, water jet cutting, laser cutting, water guided lasercutting, dry media cutting, and diamond coated wire. Water jet cuttingmay be the preferred cutting device given its small cutting width (e.g.,50 microns), its ability to shape small features, and its rapid cuttingrate. Water can also be used together with laser cutting to helpcomplement or focus its effects. As is known in the art, the abovecutting methods are able to achieve sophisticated rectilinear and/orcurvilinear shapes of the individualized integrated circuit packages. Afurther description of the cutting of integrated circuits from a paneland the shapes which may be achieved thereby is disclosed in publishedU.S. Application No. 2004/0259291, entitled, “Method For EfficientlyProducing Removable Peripheral Cards,” which application is assigned tothe owner of the present invention and which application is incorporatedby reference herein in its entirety. It is understood that thesingulated integrated circuits may be formed by other processes thanthat described above in alternative embodiments.

The shape into which each of the integrated circuits may be cut frompanel 100 may vary in alternative embodiments. However, an outline ofthe cutting shape in one embodiment is shown in dashed lines 118 on thetop view of the encapsulated panel in FIG. 4. As can be seen from theenlarged view of FIG. 5, the integrated circuits 102 are cut from panel100 so that the one or more die 114 and passive components 106 areentirely contained and enclosed within each singularized package.However, lens 112 of LED 108 is positioned within molding compound 124,such that the lens is cut during the singularization process, leaving atip of the lens separated from the singularized package. The result isthat the end of lens 112 remaining within the singularized package isflush with an outer edge of the package.

An example of an integrated circuit (“IC”) package 126 which may beobtained by the above-described process is shown in FIGS. 6 and 7. FIG.6 is a top view of an IC package 126 cut from panel 100 and includingintegrated circuit 102 encapsulated within molding compound 124 asdescribed above. IC package 126 may include a chamfer 128 in a firstcorner and a notch 130 in a corner diametrically opposed from chamfer128. IC package 126 may further include a first edge 132 adjacent tochamfer 128, which first edge joins with a second edge 134 adjacentnotch 130. FIG. 7 is a view along line 7-7 in FIG. 6 of first edge 132and chamfer 128. As seen in FIGS. 6 and 7, an end 136 of diode lens 112lies flush with edge 132 and exposed to the environment surroundingwithin IC package 126. Thus, upon activation of LED 108, light fromdiode 110 is focused by lens 112 and emitted from lens end 136 in edge132 of package 126 (as indicated by dashed lines in FIG. 6) where it maybe seen from outside the package. The LED 108 may be positioned withinIC package 126 so that the lens is oriented differently, and end 136 isflush with an edge of IC package 126, other than first edge 132.

Referring to FIGS. 5 and 6, in an embodiment, the cut tip of lens 112 inan integrated circuit 102 a resides within notch 130 of next adjacentintegrated circuit 102 b. As notch 130 in the finished integratedcircuit 102 b is cut away, the cut tip does not interfere with or formpart of the package formed by finished integrated circuit 102 b. It isunderstood that the integrated circuits on panel 100 may be cut into avariety of other shapes in alternative embodiments, with a tip of theembedded LED flush with an edge of the package. In such embodiments, thetip of the LED may be provided in a straight or rounded portion of theedge. It is also understood the cut tip from a first integrated circuitmay remain embedded in an unused portion of a second, adjacentintegrated circuit when the integrated circuits are singulated.

Referring again to the flowchart of FIG. 1 and the views of FIGS. 8-10,a completed IC package 126 may further be enclosed within an externalpackage or lid (or pair of lids) 138 in step 68. Such a lid wouldprovide an external covering for the IC package and establish externalproduct features. In one embodiment, the IC package 126 and lid 138 maycomprise a Flash Memory Card 139, such as those manufactured by SanDiskCorporation of Sunnyvale, Calif. However, it is understood that ICpackage, including embedded LED 108, may be used in a wide variety ofother flash memory and integrated circuit devices. Such devices mayinclude a Compact Flash, a Smart Media, an SD Card, a Mini SD Card, anMMC, an xD Card, Transflash or Memory Stick. Other devices arecontemplated.

In order that light from LED 108 may be visible through lid 138, some orall of lid 138 may be transparent or semi transparent as shown in FIGS.8 and 9. Alternatively, as shown in the embodiment of FIG. 10,integrated circuit package 126 may be housed within a lid 140 having anopening 142 through which light from LED 108 may shine. It is understoodthat in further embodiments of the present invention, lid 138/140 may beomitted, and integrated circuit package 126 be used without anyadditional external covering. In the embodiments of FIGS. 8-10, the LEDis located adjacent contact pins on the underside of card 139, and theLED may be obscured from view in some uses of card 139. As indicatedabove, the LED may be provided in a different edge of IC package 126 sothat it may be visible even if an end of card 139 including the contactpins is covered.

As a further device example, FIG. 11 shows a perspective view of an ICpackage including an embedded LED used in a dual interface card 180capable of use with both SD and USB interfaces. In particular, a firstend 182 is adapted for use with a USB interface, and a second end 184 isadapted for use with an SD interface. Such a dual interface card isshown and described in U.S. Utility patent application Ser. No.10/826,801 filed on Apr. 16, 2004, U.S. Utility patent application Ser.No. 10/826,796 filed on Apr. 16, 2004, and related U.S. Design patentapplication Ser. No. 29/203,693 filed on Apr. 16, 2004, U.S. Designpatent application Ser. No. 29/203,694 filed on Apr. 16, 2004, U.S.Design patent application Ser. No. 29/226,505 filed on Mar. 28, 2005,and U.S. Design patent application Ser. No. 29/226,477 filed on Mar. 28,2005. Each of these applications is incorporated by reference herein inits entirety.

The card 180 shown in FIG. 11 may include an IC package 126 having anembedded LED as described above for emitting light (as indicated by thedashed lines in FIG. 11) when the card 180 is used in the USB port.

IC package 126 including embedded LED 108 may be used in a variety ofways. For example, referring to the flow chart of FIG. 12, embedded LED108 may be used to confirm proper installation of the IC package 126into a host electronic device. In particular, IC package 126 may beinserted into a host device in step 200. In step 202, a controllerwithin the IC package detects whether proper electrical connection withthe host device is detected. If proper electrical connection isdetected, the LED is illuminated in step 204. If proper electricalconnection is not detected, the LED is not lit (step 206).

In step 208, the user of IC package 126 then checks to see whether theLED is illuminated. If it is, proper installation of IC package 126 isconfirmed (step 210). On the other hand, if the LED is not lit, thisindicates an improper installation of the IC package (step 212). The ICpackage may then be removed in step 214 and reinserted.

After installation, a lit LED may be used to indicate a read/writeoperation from/to the integrated circuit device (steps 220-222). Inembodiments, the LED may light up to indicate proper installation, andthe LED may flash on and off to show read/write operations. The reverse,as well as other lighting schemes, are contemplated It is understoodthat embodiments of the invention may include the installationconfirmation steps 200 through 214 without performing the read/writeindicator steps 220 through 222. It is also understood that embodimentsof the present invention may include read/write indication steps 220through 222, but omit installation confirmation steps 200 through 214.It is further contemplated that both installation confirmation steps 200through 214 and read/write operation steps 220 through 222 may beomitted, and LED perform some other visual indicator of a state of ICpackage 126.

In embodiments of the present invention, LED 108 emits a signal withinthe visible light spectrum. However, in an alternative embodiment, LED108 may emit a light in the infrared or ultraviolet light spectrum.Moreover, while a single LED has been shown encapsulated within package126, it is understood that two or more LEDs may be encapsulated withinpackage 126, each having an end flush with an edge of the package toemit light outside of the package. In such embodiments, the two or moreLEDs may extend to the same or different edges. The two or more LEDs mayemit the same or different colors.

In embodiments of the above-described fabrication process, eachintegrated circuit 102 on panel 100 is positioned in substantially thesame orientation as each other integrated circuit 102 on panel 100. Insuch an embodiment, a tip of LED lens 112 remains in panel 100 aftersingulation, or otherwise goes unused. In an alternative embodiment ofthe invention shown in FIGS. 13 and 14, adjacent rows of integratedcircuits 102 may be configured as mirror images of each other (or atleast be cut in mirror image shapes to each other). Such an embodimentmay use a shared LED 160 between adjacent, mirror-imaged integratedcircuits 102 c and 102 d. Shared LED 160 includes a lens 162, a diode164 adjacent a first end of lens 162 and positioned within the firstintegrated circuit 102 c, and a second diode 166 at a second end of lens162 and positioned within the second, mirror-imaged, integrated circuit102 d. According to such an embodiment, when the integrated circuits aresingulated into individual packages, lens 162 is cut as described above.Upon singulation, diode 164 and a portion of lens 162 reside within thefirst IC package and diode 166 and the remaining portion of lens 162reside within the second IC package. It is contemplated that twoadjacent integrated circuits 102 may be mirrored with respect to eachother at edges other than that shown in FIGS. 13 and 14 so that lens 162would lie flush with edges other than that shown in FIGS. 13 and 14 uponsingulation of the integrated circuits.

The foregoing detailed description of the invention has been presentedfor purposes of illustration and description. It is not intended to beexhaustive or to limit the invention to the precise form disclosed. Manymodifications and variations are possible in light of the aboveteaching. The described embodiments were chosen in order to best explainthe principles of the invention and its practical application to therebyenable others skilled in the art to best utilize the invention invarious embodiments and with various modifications as are suited to theparticular use contemplated. It is intended that the scope of theinvention be defined by the claims appended hereto.

1. An integrated circuit package, comprising: a base; one or moresemiconductor die mounted on the base; a light emitting diode mounted onthe base; molding compound encapsulating the one or more semiconductordie and at least partially encapsulating the light emitting diode, anend of the light emitting diode lying flush with an edge of theintegrated circuit package and capable of emitting light outside thepackage.
 2. An integrated circuit package as recited in claim 1, whereinthe base comprises one of a substrate, a leadframe and a tape.
 3. Anintegrated circuit package as recited in claim 1, further comprising oneor more passive components mounted on the base.
 4. An integrated circuitpackage as recited in claim 1, the LED capable of indicating a state ofthe integrated circuit package.
 5. An integrated circuit package asrecited in claim 1, further comprising at least a second light emittingdiode mounted on the base, the at least second light emitting diodebeing encapsulated in the molding compound, and an end of the at leastsecond light emitting diode lying flush with an edge of the integratedcircuit package and capable of emitting light outside the package.
 6. Aflash memory device, comprising: a base; one or more semiconductor diemounted on the base; a light emitting diode mounted on the base; moldingcompound encapsulating the one or more semiconductor die and the lightemitting diode, an end of the light emitting diode lying flush with anedge of the integrated circuit package and capable of emitting lightoutside the package; and one or more lids in which the encapsulated oneor more semiconductor die and the light emitting diode may be enclosed.7. A flash memory device as recited in claim 6, wherein the basecomprises one of a substrate, a leadframe and a tape.
 8. A flash memorydevice as recited in claim 6, the flash memory device comprising a dualSD/USB flash memory having an SD connector and a USB connector.
 9. Aflash memory device as recited in claim 8, the LED capable of indicatinga state of the flash memory device when USB connector is engaged with aUSB port of a host device.
 10. A flash memory device as recited in claim6, the flash memory device comprising an SD flash memory.
 11. A flashmemory device as recited in claim 6, the flash memory device comprisingone of a compact flash, a smart media, an SD card, a mini SD card, anMMC, an xD card, transflash or memory stick.
 12. A flash memory deviceas recited in claim 6, the one or more semiconductor die comprising aflash memory module.
 13. A flash memory device as recited in claim 6,the one or more semiconductor die comprising a flash memory module and acontroller.
 14. A method of installing a flash memory card in a hostdevice, comprising the steps of: (a) positioning the flash memory cardin the host device; (b) illuminating a light emitting diode if the flashmemory card establishes proper electrical communication with the hostdevice; (c) removing the flash memory card and reinserting the flashmemory card if the light emitting diode is not illuminated after saidstep (a) of positioning the flash memory card in the host device.